The Mohs Procedure
What is Mohs Surgery?
In Mohs surgery, the dermatologist performs the dual role of skin cancer surgeon and pathologist. The Mohs procedure involves the surgical removal of the visible portion of the skin cancer, along with a layer of the surrounding skin. This tissue is then divided into sections and color-coded by the Mohs surgeon, while corresponding reference marks are made on the patient to indicate the source from which each section was taken. The surgeon then draws a map of the surgical site, and the tissue is processed to create microscope slides for examination and analysis by the physician. He or she then examines the undersides and edges of each section microscopically for evidence of remaining cancer cells. If cancer is still present, the involved areas are carefully marked on the map and the patient is prepared to undergo removal of another layer of tissue. It is important to note that any additional tissue is removed only from the area(s) in which cancer cells are still evident on microscopic examination. This process is repeated until no further evidence of cancer remains at the surgical site.
Mohs Skin Cancer Treatment Areas
Mohs surgery treats skin cancers in anatomic areas in which preservation of the maximum amount of surrounding healthy tissue is critical for functional and/or cosmetic purposes, such as the eyelids, nose, ears, fingers, toes, and genitalia.
What cancers are treated with Mohs surgery
Mohs surgery is used to excise previously-treated skin cancers that have recurred over time, skin cancer containing scar tissue, large skin cancers, skin cancers with borders that are not clearly defined, and skin cancers that demonstrate certain unusual growth patterns. Skin cancers with aggressive subtypes, such as sclerosing or infiltrating basal cell carcinomas, also may require the use of Mohs surgery. The dermatologist will consider a number of factors in determining whether Mohs surgery is indicated for particular skin cancer.
How effective is Mohs Surgery
Clinical studies have demonstrated that Mohs surgery provides five-year cure rates approaching 99% for new cancers and 95% for recurrent cancers. Important advantages of the Mohs procedure are that it allows the greatest amount of surrounding healthy tissue to remain intact, potentially reducing the size of the final surgical defect and resulting scar; and that the methodical manner in which all lateral and deep tissue margins are examined enables the surgeon to detect and remove any “roots” of the skin cancer that may be present, which greatly reduces the likelihood of recurrence.
Mohs Training and Experience
Residency training in Dermatology provides the basic skill set from which the Mohs technique is derived: skin cancer pathology, cutaneous histopathology, dermatologic surgery, and the repair of complex surgical defects. The Mohs surgeon continues to enhance these skills in residency and once in practice through repeated observation and performance of the Mohs technique. Challenging medical education courses with an emphasis on Mohs surgery, observational preceptorship training with other highly-experienced Mohs surgeons, and formal Mohs fellowships all are available options for post-Residency Mohs training. Each experience encourages further advancement and refinement of the dermatologist’s surgical skills and enables him or her to treat progressively more complex Mohs cases.
Team Approach to Skin Cancer Treatment
In an effort to provide the best possible medical care, Mohs surgeons sometimes treat patients in partnership with other specialists such as oculoplastic surgeons, ENT (ear, nose, and throat) specialists, oral surgeons, plastic surgeons, and radiation oncologists. If indicated for your condition, your Mohs surgeon will discuss these options in detail with you.
How common is Mohs surgery?
Statistics aren’t kept as to the overall removal of skin cancer using methods such as curette removal or excision versus Mohs surgery. The incredibly high cure rates using Mohs, over 99 percent, would seem to make it the preferred method for every skin cancer removal. But it’s not right for all patients.
Mohs is the agreed upon gold standard for treatment of many basal cell carcinomas and squamous cell carcinomas, including those in cosmetically and functionally important areas around the eyes, nose, lips, ears, scalp, fingers, toes, or genitals. It is usually recommended for basal and squamous cell carcinomas that are large or aggressive, that appear in an area with little tissue beneath the lesion, and in areas that were treated with other removal methods prior and the cancer returned.
Is Mohs surgery painful?
Mohs surgery is no more or less painful than traditional excision surgery. During the procedure, local anesthesia ensures you won’t feel anything. There will be some mild discomfort as the incision heals. This usually only requires over-the-counter pain medication. These surgeries with a surgeon trained in Mohs methodology do not involve much acute pain.
How can I prepare for Mohs surgery, especially if I am nervous?
These procedures are done using only local anesthesia, as this allows the patient to leave the room or do other things while waiting for the results after the first excision. If you are especially apprehensive, sedation can be added to the process to help you relax.
What is recovery like after Mohs surgery?
Recovery from Mohs surgery is no different than any other skin excision procedure.
The extent of your wound is predicated on the size of your skin cancer and how much tissue needed to be removed. Generally, there are four possibilities:
The wound is small enough it can heal with just a bandage
The wound is closed with stitches
Skin is shifted from an adjacent area to cover the wound (skin flap)
Skin is taken from another part of the body, such as behind the ear, and is used to replace removed tissue
Wound healing and care instructions will be given to you, depending on what method was used.
Can Mohs be used on melanoma?
Mohs can be used on melanoma, but it is only used to treat an early type of melanoma called lentigo maligna melanoma. This type of melanoma stays close to the surface of the skin for a while before it begins moving downward.
For these procedures, Mohs is modified into what is called “slow Mohs.” It has this moniker because the patient must wait for their results, rather than the same-day results with basal and squamous cell Mohs procedures. Because these excisions usually involve larger areas, it’s not possible to fully test the sample to see if all the cancerous cells have been removed in the short time frame.
In slow Mohs, the surgeon removes the visible skin cancer and a bit of normal-looking skin around it. The patient is then bandaged up, without closing the wound, and sent home. The patient usually returns the next day and more tissue is removed if cancer cells were found and the process is repeated, or, if the sample edges were clear, the patient’s wound is sutured closed.
With slow Mohs, more attention needs to be placed on possible infection, since the wound stays open (although fully covered with sterile gauze and bandages) for long periods of time.
How long do you have to keep the bandages on after Mohs surgery?
After a Mohs procedure, the wound is covered with a bulky bandage called a pressure dressing. This bandage absorbs the normal oozing that occurs during the first 24 hours after surgery and prevents bleeding in the immediate post-operative period. This bandage will be left in place for 24 hours and it must be kept dry. After 24 hours, this bandage can be removed. Underneath the bandage the wound is covered with small tapes called steri-strips. These cover your sutured incision. These will stay on until they begin to peel off on their own or until they are removed when your sutures are removed.
Can I drive myself home after Mohs surgery?
Most Mohs procedures on highly localized and generally not that invasive. Barring the use of sedation, and depending on the location of your surgery, patients can drive themselves home afterward. It’s recommended, if possible, to have someone with you, however, both for company while awaiting your results and to drive your home.